Two-photon excitation spectroscopy of photosynthetic light-harvesting complexes and pigments

2019 ◽  
Vol 216 ◽  
pp. 494-506 ◽  
Author(s):  
Alexander Betke ◽  
Heiko Lokstein
Keyword(s):  
Spectral Region ◽  
Protein Complexes ◽  
Photosynthetic Pigment ◽  
Photon Absorption ◽  
Light Harvesting Complexes ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Photon Excitation ◽  
Pigment Protein Complexes ◽  
Two Photon Excitation

Two-photon excitation (TPE) profiles of LHCII samples containing different xanthophyll complements were measured in the presumed 11Ag− → 21Ag− (S0 → S1) transition region of xanthophylls. Additionally, TPE profiles of Chls a and b in solution and of WSCP, which does not contain carotenoids, were measured. The results indicate that direct two-photon absorption by Chls in the presumed S0 → S1 transition spectral region of carotenoids is dominant over that of carotenoids, with negligible contributions of the latter. These results suggest the re-evaluation of previously published TPE data obtained with photosynthetic pigment–protein complexes containing (B)Chls and carotenoids.

Two-photon Absorption and Excitation Spectroscopy of Carotenoids, Chlorophylls and Pigment-Protein Complexes

2021 ◽  
Author(s):  
Daniel A. Gacek ◽  
Alexander Betke ◽  
Julia Nowak ◽  
Heiko Lokstein ◽  
Peter Jomo Walla
Keyword(s):  
Excited States ◽  
Protein Complexes ◽  
Photosynthetic Pigment ◽  
Photon Absorption ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Pigment Protein Complexes

In addition to (bacterio)chlorophylls, (B)Chls, photosynthetic pigment-protein complexes bind carotenoids (Cars) that fulfil various important functions in which are not fully understood, yet. However, certain excited states of Cars are...

scholarly journals Phenothiazin-N-yl-capped 1,4-diketo-3,6-diphenylpyrrolo[3,4-c]pyrrole exhibiting strong two-photon absorption and aggregation-enhanced one- and two-photon excitation red fluorescence

RSC Advances ◽  
2017 ◽  
Vol 7 (49) ◽  
pp. 30610-30617 ◽  
Author(s):  
Kai Zhang ◽  
Zhongwei Liu ◽  
Shian Ying ◽  
Mingshuai Chen ◽  
Shanfeng Xue ◽  
...  
Keyword(s):  
Cross Section ◽  
Absorption Cross Section ◽  
Photon Absorption ◽  
Absorption Cross ◽  
Two Photon Absorption ◽  
Red Fluorescence ◽  
Two Photon ◽  
Photon Excitation ◽  
Two Photon Excitation

A phenothiazin-capped simple DPP dye exhibits a large two-photon absorption cross section and aggregation-enhanced one- and two-photon excitation red fluorescence.

Quantitative Imaging of Metabolism by Two-Photon Excitation Microscopy

1999 ◽  
Vol 5 (S2) ◽  
pp. 1048-1049
Author(s):  
David W. Piston ◽  
Susan Knobel ◽  
George Patterson
Keyword(s):  
Quantitative Imaging ◽  
Photon Absorption ◽  
Limiting Factors ◽  
Focal Volume ◽  
Time Resolved ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Photon Excitation ◽  
Small Absorption ◽  
Two Photon Excitation

Two-photon excitation microscopy provides attractive advantages over confocal microscopy for three-dimensionally resolved fluorescence imaging. Because of the intensity-squared dependence of the two-photon absorption, the excitation is limited to the focal volume. This inherent localization minimizes photobleaching and photodamage - the ultimate limiting factors in fluorescence microscopy of living cells. One of the most powerful applications of two-photon excitation microscopy is imaging from the naturally occurring reduced pyridine nucleotides (NAD(P)H). NAD(P)H is a useful indicator of cellular metabolism, but it is not a “good“ fluorophore (it has a small absorption cross-section and a low quantum yield). Two-photon excitation of NAD(P)H yields minimal photodamage, thus allowing time-resolved threedimensional metabolic mapping of cellular redox state. We have used two-photon excitation microscopy to examine glucose metabolism in pancreatic and muscle cells. As glucose is metabolized by these cells, intermediate metabolism results in an increase in the reduced-tooxidized NAD(P)H/NAD(P)+ ratio, and a concomitant increase in autofluorescence.

Gas Phase Two-Photon Spectroscopy of Polyazines: Pyrazine

1979 ◽  
Vol 34 (8) ◽  
pp. 979-982 ◽  
Author(s):  
I. Knoth ◽  
H. J. Neusser ◽  
E. W. Schlag
Keyword(s):  
Excited State ◽  
Gas Phase ◽  
Vibrational Frequencies ◽  
Photon Absorption ◽  
Excitation Spectra ◽  
Selection Rules ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Photon Excitation ◽  
Two Photon Excitation

Abstract The two-photon excitation spectra of gas phase pyrazine-h4 and -d 4 in the region of the S1←S0 transition are presented. The two-photon absorption which is electronically forbidden is induced by-various vibrations of ungerade parity. Because of the different selection rules for two-photon transitions hitherto unknown vibrational frequencies in the excited state 1B3u have been determined.

Two-Photon Excitation Imaging of Glucose Metabolism in Living Tissue

1997 ◽  
Vol 3 (S2) ◽  
pp. 305-306
Author(s):  
David W. Piston
Keyword(s):  
Confocal Microscopy ◽  
Collection Efficiency ◽  
Three Dimensional ◽  
Spatial Filter ◽  
Input Power ◽  
Photon Absorption ◽  
Focal Volume ◽  
Two Photon ◽  
Photon Excitation ◽  
Two Photon Excitation

Two-photon excitation microscopy (TPEM) provides attractive advantages over confocal microscopy for three-dimensionally resolved fluorescence imaging and photochemistry. It provides three-dimensional resolution and eliminates background equivalent to an ideal confocal microscope without requiring a confocal spatial filter, whose absence enhances fluorescence collection efficiency. This results in inherent submicron optical sectioning by excitation alone. In practice, TPEM is made possible by the very high local instantaneous intensity provided by a combination of diffraction-limited focusing of a single laser beam in the microscope and the temporal concentration of 100 femtosecond pulses generated by a mode-locked laser. Resultant peak excitation intensities are 106 times greater than the CW intensities used in confocal microscopy, but the pulse duty cycle of 10−5 limits the average input power to less than 10 mW, only slightly greater than the power normally used in confocal microscopy. Because of the intensity-squared dependence of the two-photon absorption, the excitation is limited to the focal volume.

Fluorescence anisotropy in indole under two-photon excitation in the spectral range 385–510 nm

2018 ◽  
Vol 20 (30) ◽  
pp. 19922-19931 ◽  
Author(s):  
M. E. Sasin ◽  
A. G. Smolin ◽  
K.-H. Gericke ◽  
E. Tokunaga ◽  
O. S. Vasyutinskii
Keyword(s):  
Propylene Glycol ◽  
Excited States ◽  
Spectral Range ◽  
Ground State ◽  
Fluorescence Anisotropy ◽  
Photon Absorption ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Photon Excitation ◽  
Molecular Ground State

This paper presents the detailed study of two-photon excited fluorescence in indole dissolved in propylene glycol produced by two-photon absorption from the molecular ground state to several high lying excited states.

scholarly journals Two-Photon–NIR-II Antimicrobial Graphene-Nanoagent for Ultraviolet–NIR Imaging and Photoinactivation

2021 ◽  
Author(s):  
WEN-SHUO KUO ◽  
Chia-Yuan Chang ◽  
Ping-Ching Wu ◽  
Jiu-Yao Wang
Keyword(s):  
Photodynamic Therapy ◽  
Quantum Yield ◽  
Chemical Modification ◽  
Near Infrared ◽  
Photon Absorption ◽  
Excitation Wavelength ◽  
Strong Electron ◽  
Two Photon ◽  
Photon Excitation ◽  
Two Photon Excitation

Abstract BackgroundNitrogen doping and amino-group functionalization, which result in strong electron donation, can be achieved through chemical modification. Large π-conjugated systems of graphene quantum dot (GQD)-based materials acting as electron donors can be chemically manipulated with low two-photon excitation energy in a short photoexcitation time for improving the charge transfer efficiency of sorted nitrogen-doped amino acid–functionalized GQDs (sorted amino-N-GQDs). ResultsIn this study, a self-developed femtosecond Ti-sapphire laser optical system (222.7 nJ pixel−1 with 100-170 scans, approximately 0.65-1.11 s of total effective exposure times; excitation wavelength: 960 nm in the near-infrared II region) was used for chemical modification. The sorted amino-N-GQDs exhibited enhanced two-photon absorption, post-two-photon excitation stability, two-photon excitation cross-section, and two-photon luminescence through the radiative pathway. The lifetime and quantum yield of the sorted amino-N-GQDs decreased and increased, respectively. Furthermore, the sorted amino-N-GQDs exhibited excitation-wavelength-independent photoluminescence in the near-infrared region and generated reactive oxygen species after two-photon excitation. An increase in the size of the sorted amino-N-GQDs boosted photochemical and electrochemical efficacy and resulted in high photoluminescence quantum yield and highly efficient two-photon photodynamic therapy. ConclusionThe sorted dots can be used in two-photon contrast probes for tracking and localizing analytes during two-photon imaging in a biological environment and for conducting two-photon photodynamic therapy for eliminating infectious microbes.

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